Which of the following is true about alpha amylase?

The correct answer is that alpha amylase cleaves 1-4 bonds at various points. Alpha amylase is an endo enzyme that acts on starch and glycogen, hydrolyzing the alpha-1,4-glycosidic bonds present in these polysaccharides. This means that it breaks the glucose polymer at multiple locations rather than solely at the ends, facilitating the conversion of complex carbohydrates into simpler sugars, which can be further fermented by yeast in brewing.

The characteristic of cleaving at various points is crucial in the mashing process during brewing, where the goal is to create fermentable sugars for yeast to consume. This property allows for greater efficiency in producing fermentable sugars compared to enzymes that might act only at the ends of sugar chains.

In the context of the other options, terminal glucose unit activity pertains more to enzymes like glucoamylase, which specifically target and act on the ends of carbohydrate chains. Alpha amylase is not a primary fermentable enzyme; instead, it prepares the substrate for fermentation. Additionally, alpha amylase typically functions optimally at higher temperatures, usually between 60-70 degrees Celsius, making the notion of it working best at lower temperatures inaccurate.